Method and apparatus for manufacturing container lids having transparent windows

ABSTRACT

AN APPARATUS FOR PRODUCING WINDOWED CONTAINER LIDS FROM A WEB OF TRANSPARENT FILM AND PREFORMED RING-SHAPED CLOSURE MEMBERS HAVING PERIPHERAL SEAL-FORMING CHANNELS FOR ENGAGING THE RIMS OF CONTAINERS COMPRISING ENDLESS SERIES OF UPPER AND LOWER DIE PLATE ASSEMBLIES ARRANGED ON FIRST AND SECOND CONTINUOUS-LOOP CONVEYORS SO AS TO BE PERIODICALLY BROUGHT INTO MATING ENGAGEMENT WITH THE FILM WEB TAUTLY DISPOSED BETWEEN. THE LOWER DIE PLATE ASSEMBLIES INCLUDE ANNULAR RECESSES FOR RECEIVING THE CLOSURE MEMBERS AND A CONTINUOUS KNIFE EDGE CIRCUMFERENTIALLY DISPOSED THERETO. THE UPPER DIE PLATE ASSEMBLIES INCLUDE A RECIPROCATIVELY MOUNTED ANNULAR   TAMPING DIE WHICH, WHEN ACTUATED, EXTENDS INTO THE PERIPHERAL CHANNEL OF THE CLOSURE RING. A STATIONARY CAM TRACK DISPOSED ABOVE THE FIRST CONTINUOUS-LOOP CONVEYOR MOMENTARILY ACTUATES THE TAMPING DIE WHILE THE DIE ASSEMBLIES ARE IN MATING ENGAGEMENT TO SEVER A WINDOW-SIZED SHEET FROM THE FILM WEB AND TAMP THE MARGINS THEREOF INTO THE PERIPHERAL CHANNEL. IMPROVED STABILITY AND ACCURACY IS OBTAINED BY THE PROVISION OF DIAGONALLY OPPOSED ROLLERS ON THE DIE PLATE ASSEMBLIES AND INTERLOCKING PIN AND SOCKET ASSEMBLIES THEREBETWEEN.

United States Patent [191 Balch et al.

[451 June 28,1974

[ METHOD AND APPARATUS FOR MANUFACTURING CONTAINER LIDS HAVING TRANSPARENT WINDOWS [75] Inventors: James L. Balch; James E. Anderson;

Charles J. Schroeder, all of Madison, Wis.

[73] Assignee: Oscar Mayer & Co. Inc., Madison,

Wis.

[22] Filed: Apr. 23, 1973 [2]] Appl. No.: 353,881

[52] US. Cl 29/208 R, 29/208 D, 29/412 [51 Int. Cl 823p 19/04, 823p 17/00 1581 Field of Search 29/208 D, 416, 412, 208 R [56] References Cited UNITED STATES PATENTS 3,221,692 12/1965 Seiferth et al. 29/416 X I 3,471,918 10/1969 Vedvik et al 29/208 R Primary ExaminerThomas H. Eager [57] ABSTRACT An apparatus for producing windowed container lids from a web of transparent film and preformed ringshaped closure members having peripheral sealforming channels for engaging the rims of containers comprises endless series of upper and lower die plate assemblies arranged on first and second continuousloop conveyors so as to be periodically brought into m'ating engagement with the film web tautly disposed between. The lower die plate assemblies include annular recesses for receiving the closure members and a continuous knife edge circumferentially disposed thereto. The upper die plate assemblies include a reciprocatively mounted annular tamping die which,

when actuated, extends into the peripheral channel of the closure ring. A stationary cam track disposed above the first continuous-loop conveyor momentarily actuates the tamping die while the die assemblies are in mating engagement to sever a window-sized sheet from the film web and tamp the margins thereof into the peripheral channel. lmproved stability and accuracy is obtained by the provision of diagonally op posed rollers on the die plate assemblies and interlocking pin and socket assemblies therebetween.

8 Claims, 10 Drawing Figures PATENTEDJUH 28 I974 8.820.219

sum 6 or 6 HIM METHOD AND APPARATUS FOR MANUFACTURING CONTAINER LIDS HAVING TRANSPARENT WINDOWS BACKGROUND OF THE INVENTION This invention relates generally to an improved method and apparatus for producing from pre-fonned ring-like closure members and a web of transparent film material windowed can lids for tray-type produce containers.

Tray-type containers, particularly those fabricated in pie-pan form of relatively thin deformable material such as thin gauge aluminum, have come into use for marketing food products such as liver sausage, meat spreads, cheese spreads, puddings and other products of various kinds. To provide a sanitary and appealing display of the contents of these hermetically sealed containers, transparent lids have been provided for the type consisting of ring-shaped closure member having a peripheral channel for engaging the rim of the container, and a window-forming transparent plastic sheet,

the latter being stretched across the closure member to form a hermetic seal therewith. A package having this structure is disclosed in U.S. Pat. No. 3,221,692 to Seiferth et al., which is assigned to the present assignee.

In producing packages of the type described, it was previously the practice to place a sheet of transparent plastic film over the mouth of the container after the container has been filled with the product, and then to position a metal closure ring derived from a conventional can lid on top of the sheet with its downwardly opening circumferential channel in alignment with the upper circumferential rim of the container. The package was then completed by means of a double seam forming operation in conventional can seaming machinery followed by a trimming operation wherein the excess film was cut away. Subsequently, a machine was devised which provided increased productivity by automatically preassembling the transparent closure sheets or windows and closure members or sealing ring into a unitary lid assembly which, once assembled, could be handled as a conventional metal can lid and assembled to the container in a single operation in the same manner and with the same machinery used for applying can lids. This machine is described in U.S. Pat. No. 3,471,918 to Andrew H. Vedvik et al., which is also assigned to the present assignee.

While the windowed lid forming machine shown and described in U.S. Pat. No. 3,471,9l8 performed well for its intended purpose, it relied on a sequence of individual operations which had to be performed serially SUMMARY OF THE INVENTION Accordingly, it is a general object of the present invention to provide new and improved apparatus for manufacturing a transparent lid for a tray-type container.

It is another general object of the present invention to provide a new and improved method for manufacturing a windowed container lid.

It is a more specific object of the present invention to provide apparatus for manufacturing a transparent sealing lid which apparatus exhibits improved performance and an increased production rate.

Another more specific object of the present'invention is to provide apparatus for continuously feeding a web of film material from a supply reel, cutting from the film sheets of predetermined size and shape while positioned over successive ring-shaped closure members, and tamping the margins of the sheets into the circumferential channels on the closure rings for contact with the sealing composition therein whereby the transparent windows are held in position. I

A further object of the invention is the provision of improvements in the apparatus and method of producing windowed can lids shown and described in U.S. Pat. No. 3,471,918.

Accordingly, the invention is directed to apparatus for placing a window-formingsheet of flexible film material in a container closure member having a peripheral composition lined channel portion adapted for cooperation with the top margin of a container in forming a seam for attaching the closure member to the container. The apparatus comprises a first die plate having an annular recess for receiving the closure member, a second die place having a tamping member complementarily shaped to the composition lined channel portion of the ring-shaped closure member and reciprocatively mounted on the second die plate for selectively extending into and out of the channel, and a continuous-loop conveyor means for moving the first and sec- 0nd die plates into and out of temporary mating engagement. Means are provided for delivering a film in web form between the first and second die plates, the film being captivated therebetween while the die plates are matingly engaged, and means comprising a cutting edge disposed about the periphery of the second die plate adjacent the outside circumference of the closure member-receiving recess are provided for cutting a sheet of film from the web when the tamping member is extended. Means are also provided for extending the tamping member into the seam forming channel while the die plates are in mating engagement to cut the portion of the film overlying the closure member from the film web and seat the peripheral margin thereof into the seam forming channel.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with the further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is a perspective view from the feed end of an apparatus constructed in accordance with the invention for manufacturing windowed lids of the class described for tray-type containers. FIG. 2A is a top view of a transparent lid of the type produced by the apparatus of FIG. 1.

'FIG. 2B is a cross-sectional view on enlarged scale taken along lines 2B-2B of FIG. 2A.

portion of the apparatus of FIG. 1 showing the coaction of first and second continuous-loop conveyors in bringing upper and lower die plate assemblies into mating engagement.

FIG. 4 is a cross-sectional view taken along lines 4-4 of FIG. 3.

FIG. 5 is a cross-sectional view on an enlarged scale taken along lines 55 of FIG. 3.

' FIG. 6 is a bottom plan view of one of the top die plate assemblies shown in FIG. 1.

FIG. 7 is a top plan view of the bottom die plate assembly shown in FIG. 1.

FIG. 8 is a fragmentary side elevational view showing two pair of top and bottom die plate assemblies in mating engagement.

FIG. 9 is an elevational view of the apparatus taken from the back side as shown in FIG. 1 and showing the drive chain arrangement utilized for powering the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, an apparatus is illustrated for assembling windowed covers or lids for tray-type containers. While the apparatus can be adapted to assemble windowed covers of various sizes and shapes, it is particularly well suited for assembling lids for pie-pan shaped containers-of the typetypically employed for containing food products such as meat spreads and cheese spreads, and'will accordingly be shown configured for assembling round lids such as that shown in FIGS. 2A and 2B.

Referring to FIG. 2A, the windowed lid is seen to consist of a ring-shaped closure member 10 derived from a conventional metal can lid by having its center portion removed so as to permit the contents of a package to which it is attached to be observed through a transparent film window 11 which cooperates with the closure member 10in forming a cover or lid for an underlying container. The closure member ring 10, as shown inverted in FIG. 28, comprises a relatively narrow inner flange 12 which extends inwardly from a generally cylindrical wall section 13, the latter constituting the inner side of a seam-forming channel 14 which has its outer side 15 curved upwardly and inwardly to tightly engage the rim of a container (not shown). A cover'sheet 16 of a transparent film, such as Myler" or Saran," having its marginal portions extending into the seam forming channel 14, extends across the center opening of the closuremember 10 to form a transparent air-tight cover for the container. The seam forming channel 14 is lined in a known manner with a suitable adhesive or sealing material 17 of known type along its bottom face to perfect the hermetic seal formed on seaming to better secure the cover sheet 16 to the closure member 10. This sealant I7 is normally provided to increase the effectiveness of the container seal when the closure member is seamed on the rim of the container.

Referring now to FIGS. I and 3, an apparatus constructed in accordance with the invention for assembling container lid assemblies such as that shown in FIGS. 2A and 2B is seen to comprise an upright frame 20, an endess series of lower die plate assemblies 21, an endless series of upper die plate assemblies 22, and a magazine-type loader 23 for feeding the ring members- 10 into the machine.

The lower die plate assemblies are supported on first conveyor means in the form of a pair of laterally- Y spaced chains 24 and 24' which extend nearly the full length of frame 20. The chains 24 and 24 are supported at opposite ends by axially spaced pairs of sprocket wheels 25 and 26 carried on supporting shafts 27 and 28 individually joumaled to frame 20. The individual lower die plate assemblies 21 are guided by rollers 30 and 31 disposed at diagonally opposed corners of the assemblies, the rollers engaging upper and lower guide rail pairs 32 and 32, and 33 and 33', while the die plate assemblies are moving along their upper and lower horizontal runs, respectively. The edges of pairs of parallel end plates 34 and 34, located at respective ends of the lower conveyor means, are provided with appropriate contours for engaging rollers 30 and 31 to provide guidance as the lower die plate assemblies transistion between their upper and lower runs.

The upper die plate assemblies 22 are conveyed by a shorter conveyor means having generally the same structure as that provided for the lower die plate assemblies. Specifically, the upper die plate assemblies are attached to a pair of laterally spaced drive chains and 40' which guide the die plates in spaced-apart relationship around a continuous-loop extending only over a portion of the length of frame 20. The chains 40 and 40'are supported at opposite ends by axially spaced pairs of sprocket wheels 41 and 42 carried on supporting shafts 43 and 44 journaled to frame 20. The individual upper die plate assemblies are guided by rollers 45 and 46 disposed at diagonally opposed corners of the assemblies, the rollers engaging guide rails 32 and 32 during the lower horizontal run and the edges of parallel spaced-apart end plate pairs 50 and 51 between upper and lower runs. As will be seen presently, the guide rails guide the upper die plate assemblies 22 in an endess path having a lower horizontal run in which the upper dieplate assemblies 22 are brought into mating engagement or lid-forming relation with the lower die plate assemblies 21.

Referring now to FIGS. 5 and 7, each lower die plate assembly 21 is seen to include a generally rectangular block or casting 52 having integral depending mounting ears 53 and 54. Each mounting ear includes a horizontal bore supporting pins 55, the latter being at tached to links indrive chains 24 and 24 for support thereby. Guide rollers 30 and 31 (FIG. 1), outwardly extending from raised bosses on die block 52, engage guide rails 32 and 32 respectively, which it will be recalled support the upper die plate assemblies 22 on their lower run and the lower die plate assemblies 21 on their upper run. It will be appreciated that while matingly engaged the upper and lower die plate assemblies are each supported by two rollers at opposite corners of their respective castings, rollers 30 and 45 simultaneously engaging guide rails 32' (roller 30 being the leading roller) and rollers 31 and 46 simultaneously engaging guide rail 32 (roller 46 being the leading roller).

Each lower die plate assembly 21 includes a cylindrical lower die plate 56 secured within a counter-bored opening in die block 52 by means of one or more expansion rings 57 or other suitable means. Die plate 56 includes an enlarged central bore 58 and an annular raised shoulder portion 60 about the circumference of the bore 58. Adjacent the periphery of the shoulder portion 60 an annular recessed channel portion 61 is provided for receiving the ringshaped closure member 10, and adjacent the outer side wall of this channel, lodged in a circular recess 59 formed between die block 52 and die plate 56, a continuous circular sawtooth cutting band 62 is provided with its teeth extending upwardly from recess 59. The die block casting 52 includes in spaced-relationship to the outside circumference of the cutting band 62 a wedge-shaped annular channel 63 for receiving an O-ring type gasket 64 which, as will be seen presently, cooperates with an annular gasket 80 on the abutting upper die plate assembly 22 to secure the window film sheet in position as it is Tamped to the closure member.

Each upper die plate assembly 22 includes a generally rectangular casting 70 having a pair of spacedapart projecting mounting ears 7] and 72. Each of the ears contains a horizontal bore for receiving support pins 73, the latter being attached to links of the upper conveyor drive chains 40 and 40'. Die block 70 is bored to receive a cylindrical tamping die member 74 in the form of an inverted cup. As shown in FIG. 6, the working portion 75 of tamping die 74, i.e., that portion which extends to the working surface of the upper die block assembly, is annular in form and stepped so as to have a ring-shaped annular raised portion 76 along its outside circumference and an annular recessed portion 77 along its inside circumference.

Tamping die 74 is slidably mounted in die block 70 so as to be reciprocable from a retracted position wherein the raised portion 76 of the die is flush with the working face of the die plate assembly 22, to an extended position wherein portion 76 extends down into the closure member receiving recess 61 in lower die plate assembly 21. To provide lateralguidance to the reciprocatively mounted tamping die member 74, a cylindrical central support member 78 is mounted within the inside circumference of the tamping die. The outside surface of this support 78 is substantially flush with the working surface of the die plate assembly 22. An annular gasket 79 fastened on the surface of the center guide member 78 coacts with the annular portion 60 of the lower die plate assembly 21 to secure the covering film 11 during the cutting and tamping process. A washer-shaped annular gasket 80 adherently received in a shallow annular recess provided about the periphery of the die block casting 70 coacts with the "O ring gasket 64 in providing additional restraint for the film.

serve to constrain the piston to reciprocate within defined limits, while the reduced width of the slots prevent the tamping die 74 from undesirably turning about its axis during operation of the apparatus. In practice, four pins 91 may be provided, preferably at each of the four quadrants of the bore in die block casting 70 to maintain the center guide member 78 accurately centered within the upper die block casting bore. To further assist in maintaining the taming die in alignment, the center guide member 78 contains a cylindrical stem 95 of reduced diameter which is slidably received within a complementarily dimensioned bore 96 and sleeve bearing 97 on the inside surface of the die 74. The effect of this provision is to stabilize the reciprocative motion of tamping die 74 and to prevent misalignment during operation of the apparatus. The top portion of the tamping die 74 includes a pair of spacedapart ears 98 and 99 which are horizontally bored to receive a pin 100 therebetween. A cam follower roller 101 is mounted on pin 100 for the purpose of actuating or extending the tamping die 74 during operation of the apparatus.

To provide positive alignment between the upper and lower die plates the upper die plate assembly is provided with a pair of alignment pins or dowels 102 and 103 situated on either side of the die block casting 70. These alignment probes extend through appropriately sized bores in housing 70 and extend downwardly sufficiently to engage respective ones of complementarily sized apertures 104 and 105 in the lower die block casting 52. When the probes 102 and 103 are received in apertures 104 and 105 positive alignment of the upper and lower die plates is assured.

Probe 102 also extends vertically upwardly to serve as a mounting means for a roller 106. This roller bears against the inner vertical surface of the adjacent side plate 107 provided on the side of the upper conveyor means to provide anti-sway stabilization for the upper die plate assembly 22. Roller 106 is preferably mounted on a reduced-diameter portion of pin 102, and may be secured in place by a C-washer or other appropriate fastening means. Similarly, guide pin 103 extends upward to support an anti-sway roller 108, the latter bearing against a side plate 109 provided adjacent the other side of the conveyor.

To maintain the cylindrically shaped tamping die 74 in its retracted position a helical compression spring 110 is provided within the housing of die 74. This spring bears against the top inside surface of die 74 and the top surface of center guide member 78. Since the latter element is fixed to the upper die block 70 by means of pins 91, the effect of spring 110 is to bias die 74 against the bottom ends of the elongated slots 93, thereby maintaining the tamping die 74 in its retracted position. Of course, upon depression of cam follower roller 101 with sufficient force the effort of spring 110 can be overcome and the die 74 can be forced into its extended position.

Additional support may be provided to each lower die plate assembly 21 by an additional pair of guide rollers 111 an 112 disposed in diagonally opposed corners of die block casting 52. These rollers engage additional guide rails (not shown) as the lower die assemblies proceed along their upper horizontal run to provide additional lateral support for more accurate fabrication of the container covers.

Referring now to P16. 8, the windowed lid-forming apparatus of the invention is seen to include an upper cam track 113, which extends above the lower horizontal run of the upper die plates in parallel relation thereto. This cam track is arranged to engage each cam follower 101 as the upper die plates 22 move along their lower horizontal run, and is provided with an extended actuating portion 114 such that each tamping die 74 is forced into its extended position as its cam follower roller 101 is engaged thereby. This causes the stepped portion 76 of the die 74 into the underlying recess 61 of the bottom die plate which, when a closure member is in position, results in a window 11 being cut from the film web and the marginal edges thereof being tamped in the sealing recess of the closure member 10. The length of the actuating portion 114 of the cam track determines the duration of the tamping cycle, and the height of portion 114 determines the pressure applied. Both may be adjusted as required for optimum sealing action.

Referring now to FIG. 4, the relationship between the lower and upper die plate assemblies 21 and 22, their drive chains 24, 24 and 40, 40', and the sprocket wheels 25 and 41 for tensioning the drive chains is shown. The upper die plate assembly 22 is seen to be supported by roller 45, which rests on the guide rail 32, and the lower die plate is shown to be supported by roller 31 as it rests on guide rail 32. Rollers 46 and 30 also support the die plates, but do not appear in this cross-sectional view. The upper die plate assembly is seen to be coupled by mounting ears 71 and 72 to the spaced-apart drive chains 40 and 40' which are in turn carried by double-sprocketed wheel 41 on shaft 43. The cam follower roller of the cup-shaped tamping die 74 is seen to bear against cam track 113 which is disposed above the bottom run of the upper die conveyor assembly. The anti-sway rollers 106 and 108 bear against the left and right side plates 107 and 109, respectively, of the conveyor assembly to maintain the upper die plate assembly 22 in more accurate alignment.

The lower die plate assembly 21 is engaged to the upper dieplate assembly 22 at this point, and is driven by drive chains 24 and 24' by way of mounting ears 53 and 54 carried on the bottom of die block casting 52. Drive chains 24 and 24' are in turn carried by a blocksprocket wheel 25, which is carried on transverse shaft 27 journaled at either end to the frame of the apparatus.

The closure member magazine 23 shown in FIGS. 1 and 3 comprises two pairs of vertical posts 120 spaced so as to accommodate a stack 121 of inverted ringshaped closure members 10. The posts 120 are spaced apart and secured at their lower ends to frame 20 with the bottom end spaced above the underlying bottom die plate assemblies so as to provide clearance for feeding the bottom closure member from the stack. Three spirally grooved feed or drop rolls 122 (FIG. 3) are disposed at the bottom of the magazine so as to receive the bottom closure member in the stack and by rotation thereof to separate the lowermost member and drop it into the closure member receiving channel 61 of the lower die plate assembly 21 then in position. By virtue of the interconnecting drive assembly between shaft 27 and the three spiral feed rolls I22 synchronizm is maintained between the positioning of the bottom die plate assemblies 21 and the point at which the closure members 10 are dropped. Specifically, this arrangement comprises a chain drive 123 (FIG. 1) connecting the three feed roll shafts and a right angle drive 124 which translates the rotary motion of shaft 27 to the drive chain assembly. A more detailed description of the structure and operation of magazine 23 may be had by reference to the aforementioned US. Pat. No. 3,471,918. It will be appreciated that other types of loading arrangements are possible for the closure members 10, such as an infeed conveyor which deposits individual closure members on the lower die plate assem- 8 blies 21 as they move along theirupper horizontal run towards engagement with the upper die plate assemblies 22.

A preferred arrangement for driving the apparatus is shonw in FIG. 9. There, a motor is connected to a right-angle drive 131, the output of which is connected by a chain belt 132 or other suitable means to drive shaft 28, which drives chains 24 and 24' of the lower conveyor assembly. This shaft is in turn coupled by a chain belt 133 or other suitable means to drive shaft 44 of the upper die plate conveyor assembly. As mentioned previously, power is provided to the feed rollers 122 of magazine 23 by means of a rotational coupling between those members and shaft 27, the latter being effectively coupled to shaft 28, and hence motor 130, by way of the drive chains 24 and 24' of the lower die plate assembly conveyor.

A continuous web of film material is withdrawn from a supply roll 141 by mating engagement of the upper and lower die plate assemblies 22 and 21. The supply roll 141 is mounted on a shaft 142 journaled to vertical spaced-apart extensions of frame 20, and the film is threaded downwardly over idler rollers 143 and 144 (FIG. 9) so as to run horizontally between the upper and lower die plate assemblies.

The web is drawn between the working faces of the upper and lower die plates as the latter come into engagement. The scrap which results after the window sheets 11 have been cut from the web 140 advances to a point near the endof the upper run of the lower conveyor where it proceeds around idler rollers 145 and 146 and up to a driven collecting reel 147. Reel 147 is mounted on a shaft 148 which is journaled between additional spaced-apart vertical extensions of frame 20 and includes a sprocket 149 (FIG. 1) driven by a spring belt 150 or other suitable drive means from the drive shaft 44 of the upper conveyor.

. in operation, the ring-like closure members 10 are stacked in magazine 23 and a continuous web of film material is provided from supply reel 141 as previously described. As the bottom die plate assemblies 21 are moved beneath magazine 23 by the first or bottom conveyor means the rings 10 are dispensed with upwardly facing channels, one at a time into the annular recesses 61 of successive ones of the bottom die plates 21. As the bottom die plate assemblies proceed along their top horizontal run individual ones of the top die plate assemblies 21 are brought into opposed mating engagement by the second or upper conveyor means. At the same time the web of transparent plastic material 140 is drawn between the upper and lower die plates. While the upper and lower die plates are engaged, the tamping die 74 on the upper die plate assembly 22is actuated to its extended position by cam plate 113 to force the tamping die downward onto the ring-shaped closure member 10 then positioned in the closure member receiving recess 61 of the opposed lower die plate 21. This causes the saw-tooth knife band 62 disposed on the lower die plate about the outside periphery of channel 61 to cut a closure ring-sized sheet from the film web. At the same time, the protruding portion 76 of the tamping die tamps the margins of the sheet 11 into the seal-forming composition 17 lining the bottom of channel 14 of the inverted closure member 10. The adhesion between the film and composition is sufficient to retain the window in place. The upper and lower die plate assemblies continue along their horizontal run until the upper die plate assemblies reach the return end of 1 the conveyor, at which time they separate, allowing the unused film webbing to be stripped by takeup roller [47 and the completed container covers to be removed, preferably by compressed air, and conveyed away from the apparatus by means of a suitable outfeed conveyor 151.

It will be recalled that upper die plate assembly 22 includes a resilient rubber collar 80 disposed about the periphery of tamping die 74 and an additional continuous rubber seal 79 adjacent the inside periphery of the recessed portion 77 of the tamping die. When the upper and lower die plate assemblies are in engagement these' continuous sealing rings are resiliently pressed into enggement with O-ring 64 and the raised collarlike portion 60 of the lower die plate assembly to hold the transparent film web taut between the die plates and cause it to advance therewith. This secure engagement of the film web is necessary for optimum cutting of the film 140 by the knife edge 64, and to prevent wrinkling or dislocating of the film web in the work station.

As the marginal flange portions of the upper and lower die plates come into contact in the manner just described, the guide pins 102 and 103 extending from the upper die plates are received in the sleeves 104 and 105 of the lower die plates. This engagement of the guide pins, together with the aforedescribed lateral stabilization of the diagonally opposed guide roller pairs 30, 31 and 45, 46, and the anti-sway stabilization of guide rollers 106 and 108, provides very positive alignment of the die plates and further adds to the accuracy of the assembly process."

Thus, a novel apparatus has been shown and described for forming, in one continuous operation, windowed covers or lids for tray-shaped food containers or the like. Through the provision of dual conveyors for bringing complementarily-shaped die plates into mating engagement, the transport film material for the window portion of the lids is held in position so that in a single stroke of a single tamping die the film can be separated from a supply web and tamped into position around a preformed ring-like closure member. After the film and the closure member have been joined, the completed cover is freed from the machine and conveyed away by an out-feed conveyor. Waste webbing material is accummulated for easy disposal, and loading of additional pre-formed closure members on the machine is facilitated by a novel magazine assembly. Accurate alignment of the dies is assured by a novel arrangement of cam tracks and follower wheels which provide lateral anti-sway stabilization as well as vertical and horizontal stabilization. The provision of a cam track above one of the convyeyors obviates the need for a separate piston and hydraulic or pneumatic actuator system, the motion of the upper die assemblies along the upper conveyor providing the necessary power and synchronization for extension of the tamping die. Thus, a novel and simple apparatus is achieved which provides substantially increased production efficiency an improved accuracy in forming a windowed container lid.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. Apparatus for placing a window-forming sheet of flexible film material in a container closure member having a peripheral channel portionadapted for cooperation with the top margin of a container in forming a seam for attaching the closure member to the container, said apparatus comprising, in combination:

a first die plate having a recess for receiving said closure member;

a second die plate having tamping member complementarily shaped to said peripheral channel portion of said closure member and reciprocatively mounted to said second die plate for selectively extending into and out of said peripheral channel;

continuous-loop conveyor means for moving said first and second die plates into and out of temporary mating engagement;

means for delivering a film in web form between said first and second die plates, said film being captivated therebetween while said die plates are eng means comprising a cutting edge disposed about the periphery of said second die plate adjacent the outside circumference of said closure memberreceiving recess for cutting of window of film from said web as said tamping member is extended; and

means for extending said tamping member into said peripheral channel while said die plates are in mating engagement to cut the portion of said film overlying said closure member from said film web and seat the peripheral margin thereof into said peripheral channel.

2. Apparatus as defined in claim 1 wherein said closure member is formed by removing the panel portion of a conventional metal can lid leaving a ring-shaped member including the gasket channel portion of the can lid.

3. Apparatus as defined in claim 1 wherein said conveyor means comprise a first continuous-loop conveyor for conveying a plurality of said first die plates, and a second continuous-loop conveyor for conveying a plurality of said second die plates.

4. Apparatus as defined in claim 3 wherein said tamping member includes a cam follower and said actuating means comprise a cam track in operative engagement with said cam follower whereby said tamping member is actuated by motion of said second conveyor as it moves said second die plate into mating engagement with said first die plate.

5. Apparatus as defined in claim 3 wherein said upper run of said first continuous-loop conveyor engages said lower rung of said second continuous-loop conveyor, wherein said upper run of said first conveyor is longer than said lower run of said second conveyor, and wherein means are provided for inserting said closure members in said channel portions of said first die plates as said first die plates are conveyed along said upper run of said first continuous-loop conveyor.

6. Apparatus as defined in claim 3 wherein dispensing means are provided for directing said web of film between said first and second continuous-loop conveyors.

7. Apparatus for placing a window-forming sheet of flexible film material in a container closure member having a peripheral channel portion adapted for cooperation with the top margin of a container in forming a seam for attaching the closure member to the container; said apparatus comprising, in combination:

first and second coacting die plates adapted for mating engagement, said first plate having a recess for receiving said closure member, and said second die plate having a tamping member complementarily shaped to said peripheral channel portion of said closure member and reciprocatively mounted to said second die plate for selectively extending toward and away from said channel, and a cutting edge disposed about the periphery adjacent the outside circumference of said closure memberreceiving recess, wherein upon actuation of said tamping member a window is cut from said film web and the margins thereof are seated in said seam forming portion of said closure member.

8. In the method of forming can lids having windows formed of flexible film wherein a web or sheet of the flexible film is stretched taut over the open side of the circumferential gasketed channel in a ring member formed by removing substantially the entire center panel portion of a can lid and over a circumferential knife edge embracing said ring member and an annular tamping element is pressed against said taut film so as to sever said window from said web or sheet and tamp the margin thereof into said gasketed channel, the improvements, which comprise supporting and continuously moving said ring member in a generally horizontal plane, and maintaining said tamping element in registration with said gasketed channel said tamping element is moved into pressing relation with said film.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 20,219 Dated June 28, 1974 Inventor(s) James L. Balch, James E. Anderson and Charles J.

Schroeder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 10, "produce" should be --product--.

Col. 1, line l9, "for" should be of. 7

Col. 1, line 21, after "of" insert ----a-.

Col. 1, line 42, "ring" should be -rings-.

Col. 2, line 29, "place" should be -plate.

Col. 2, line 32, "on" should be to-.

C01. 4, line 16, "34" (second occurrence) should be --35-. C01. 5, line 43, after "annular" insert raised. Col. 5, line 55, 92" should be -93-.

Col. 5, line 66, "taming" should be --tamping.

Col. 6, line 51, "an" should be --and-.

Col. 7, line 35, "block" should be -double-.

Col. 8, line 5, ."shonw" should be shown---..

Col. 9, line 20, after "film" insert -web.

Col. 9, line 39, "transport" should be transparent-. Col. 9, line 54, "convyeyors" should be -convey0rs.

Col. 10, line l3, after "having" insert a--. Col. ll, line 8, after "first" insert -'-die-I.. Col. 12, line 16, after "channel" insert --as-.

Signed and sealed this 17th day of September 1974.

(SEAL) Attestt MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents :ORM pomso (10459) uscoMM-oc some-mm 0 ll 5 GOVERNMENT FRINYING OF ICE: I969 0-'!56 H4. 

